The invention pertains generally to tilters for horizontal blinds and more particularly to a tilter utilizing a high gear ratio, a split wheel and a snap-on cradle.
Previously, many types of tilters have been used to provide an effective means for producing the required rotational motion to open and close the slats of a horizontal venetian blind. In some prior art the slats are partially rotated by a worm gear driven tilter at is actuated by a wand. The wand is rotated by a user""s hand twisting the wand in the desired direction, thus permitting the movement to be transmitted by way of an endless screw which is located at fight angles to a spur-like gear.
Other patented devices utilize horizontal blinds that use a pulley, drum or an irregular shaped tilt rod on which a pair of cords or lines are attached. By pulling either one of the cords or lines an actuator is rotated, thus rotating the tilt rod proportionally to the line linear movement.
A search of the prior art did not disclose any patents that read directly on the claims of the instant invention, however the following U.S. patents are considered related:
U.S. Pat. No. 5,680,892 issued to Liu discloses a slat angle adjusting device which has a body with a positioning member mounted on an upper side with two C-shaped forked ends, each mounted on one of the upper bent portions of a head rail. A roller is mounted in the head rail and attached to the outside of the body.
U.S. Pat. No. 5,647,422 issued to Weng is for a vertical blind assembly with a two piece housing. Two worm gears engage each other within the housing and a post is coupled to one of the worm gears for rotation. A beam is engaged to the other worm gear so as to be rotated by the post. A number of casings slideably engage the beam, and a pole supports a plurality of slats. The casings are secured to the housings by a number of couplers easily disengagable from the housings.
Lui in U.S. Pat. No. 5,636,677 teaches a slat angle adjusting device for a Venetian blend that includes a pair of casings coupled together with a pinion mounted therein. A worm and drive gear interface together with a drive axle formed in one end of the drive gear, extending outward from the casing. A bracket extends upward and a roller is mounted on the drive axle and is received between side walls of the bracket.
U.S. Pat. No. 5,341,865 issued to Fraser, et al., teaches a tilt roll mechanism with an asymmetrical cross section and includes bearings on a support that connects flexible cords of ladder laces that extend around a body. Control means are accomplished using a worm gear that engages a pinion, with appropriate number of teeth on the worm gear to prevent overtilting.
Rap, et al., in U.S. Pat. No. 5,297,789 discloses a tilter mechanism for a venetian blind that employs a fixed hollow drum secured to a head rail, and a hollow rotary mechanism that is positioned in the drum. A tilt cord is wound around the pulley and when pulled downward tilts the entire head rail thereby tilting the attached slats.
U.S. Pat. No. 4,821,789 issued to Van Rens is for a tilt drum which secures the upper ends of a cord ladder.
Valle, et al. in U.S. Pat. No. 4,676,292 teaches a tilter mechanism that uses a spur gear with a smooth peripheral portion having no teeth and a worm gear that engages the teeth for rotation by a wand.
For background purposes and as indicative of the art to which the invention is related reference may be made to the following remaining patents.
Much of the prior art in today""s marketplace is related to a tilter mechanism using a wand or a rigid operating rod for actuating the angular position of slats, which are employed in horizontal or venetian blinds. While this type of manual adjustment is the accepted method, the are many advantages to using a pair of lines or cords for actuation, as a similar type of control is commonly used to raise or lower the blinds. It is therefore, the primary object of the invention to employ a tilter mechanism that changes the tilt angle of the slats by using a pair of cords or lines each rotating the slats in an opposite direction using an elevated start gear ratio. Normally a one-to-one gear ratio is used in the venetian blind industry for rotating slats with a wand and it may be clearly seen that a faster ratio has advantages in this application.
An important object of the invention is that a separate cradle or adapter is used which mounts a tilter to the blind head rail through a square or rectangular hole located on a bottom section of the head rail. The cradle is removable from the main body or housing of the invention using a snap fastener type pin and socket, which allows the cradle to be easily interchanged. The purpose of its exchange ability is to permit the cradle to be colored to match the head rail of the blind, and, since the housing is hidden inside the channel-shaped rail, only the bottom of the device is visible. This object permits the use of a housing and gears of any color to be used in various applications while only the cradle requires changing to match colors. Since the cradle is simply snapped into place this change may be made easily, and stocking of many different colored devices is unnecessary since the relatively inexpensive removable cradle is the only element that must be color-coordinated. These features greatly increase the inventions desirability from an overall monetary viewpoint.
Another object of the invention is that the entire tilter may be made of thermoplastic, which is formed in quantity by the injection molding process. While the initial cost of tooling is relatively high, the piece price is basically low, therefore, economies of number are greatly enhanced with this invention.
Still another object of the invention is directed to the use of a split wheel to wind the lines or cords. Many types of venetian blinds use a single wheel for multiple cords which can easily become tangled or fouled ultimately causing extreme annoyance to the user. Since the wheel is split and each line has its own path separated by a physical barrier, and taken in conjunction with the fast acting gears which reduce the amount of winding necessary, any potential problem is greatly eliminated.
A final object of the invention is that the angle of the blind is controlled in increments by the use of teeth in the wheel gear shaft and a incremental positioning bushing located in the housing. This arrangement prevents backlash and permits the user to select the desired angle by the feel of the cords as they have an infinite number of stopping positions as the cord is pulled.
These and other objects and advantages of the present invention will become apparent from the subsequent detailed description of the preferred embodiment and the appended claims taken in conjunction with the accompanying drawings.